The Crested Caracara continued its long-term game of peekaboo with birders this week, turning up this time at the Duck Harbor Beach overwash in Wellfleet. True to form, the demure bird only allowed itself to be seen for about 24 hours before disappearing again. Meanwhile, the famous Swallow-tailed Kites of Mashpee and Cotuit made their last laps around the area, with one seen in Mashpee as recently as yesterday, now the latest sighting ever for Massachusetts. But I’m not here to talk about these preening prima donnas – if I give them any more airtime, they’ll be looking for a Netflix deal. This week, it’s time to give the shorebirds their due.
Welcome to that glorious time of year when parking lot attendants find themselves unemployed and us locals can beach hop at will. To sweeten the pot, it’s also the best time to catch the spectacle of southbound shorebird migration here on the Cape and Islands. Back in June, dozens of species of sandpipers and plovers were hunkered down on faraway tundra to raise their kids in the brief Arctic summer while dodging hungry jaegers and Arctic Foxes. Now they are moving south en masse, gathering on worm-rich rich mudflats and marshes to gorge and fuel trips to as far away as southern South America.
Over the years, 48 species of sandpipers and plovers have been recorded on the Cape in the month of September. Some of those are either extremely unlikely, like the Eurasian Curlew, or extinct, like the Eskimo Curlew. Basically, don’t plan on seeing a curlew. Unless it’s a Whimbrel, which is a curlew, but we don’t call it a curlew for some reason. You’ll probably see a Short-billed Dowitcher, which as a long bill, but probably not a Long-billed Dowitcher, which has a similarly long bill. And most of the Black-bellied Plovers won’t have black bellies and none of Spotted Sandpipers have spots now. Got it? I’m starting to see why beginner birders hate shorebirds.
Ah, but I kid – it’s not so bad. Only about 25 shorebird species are likely in the best shorebird spots, like around Monomoy, with some effort and luck. Start by learning the common and widespread ones, like Semipalmated Plovers, Sanderlings, and Willets. Watch how they feed, how they move - plovers use their big eyes to search the flats, running and stopping like a robin working a lawn for earthworms. Sandpipers, on the other hand, use their nerve-packed bills to probe for invertebrates, like the classic sewing machine feeding motion of a Short-billed Dowitcher. Special receptors in their bills called Herbst corpuscles sense tiny vibrations from invertebrates down in the sand and mud, then they can open just the tip of their long bills and snag it.
Look for tall, grayish Willets on south facing beaches or marshes full of fiddler crabs, where you might also see Whimbrels, big and loud with their long, curved bills. Tiny, brownish Least Sandpipers are the smallest of the lot – look for single and small groups popping up from salt marsh interiors with their short, trilled calls. Grayer Semipalmated Sandpipers prefer flats and beaches, sometimes massing by the hundreds in favored locations, fattening up for their flight to wintering beaches in Brazil.
I think I’ve given you enough shorebird homework for now, I don’t want to overwhelm you. As for me, I’ve got a serious scientific experiment to conduct. I’m heading down to the clam flats to stick my face in the mud – I want to see if I have any Herbst corpuscles.
